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Abstract We showcase an innovative campaigning and business-focused approach to reservoir monitoring of multiple fields using 4D (time-lapse) seismic. Benefits obtained in terms of cost, speed and the quality of insights gained are discussed, in comparison with a piecemeal approach. Challenges and lessons learned are described, with a view to this approach becoming more widely adopted and allowing 4D monitoring to be extended to smaller or more marginal fields. An offshore seismic acquisition campaign was planned and successfully executed for a sequence of four 4D monitor surveys for fields located within 250 km of each other on the greater Northwest Shelf of Australia. The four monitors were acquired in H1 2020 comprising (in this order): Pluto Gas Field M2 (second monitor), Brunello Gas Field M1 (first monitor), Laverda Oil Field M1 and Cimatti Oil Field M1. Cost savings expected from campaigning were realised, despite three cyclones during operations, with success largely attributed to detailed pre-survey planning. Also important were the choice of vessel and planning for operational flexibility. The baseline surveys were diverse and required careful planning to achieve repeatability between vintages over each field, and to optimise the acquisition sequence – minimising time required to reconfigure the streamer spreads between surveys. The Cimatti baseline survey was acquired using a dual-vessel operation; modelling, combined with now-standard steerable streamers, showed a single-vessel monitor survey was feasible. These optimisations provided cost savings incremental to the principal economy of sharing vessel mobilisation costs across the whole campaign. Both processing and evaluation (ongoing at the time of writing) are essentially separate per field, but follow a consistent approach. Processing is carried out by more than one contractor to debottleneck this phase, with products, including intermediate quality control (QC) volumes, delivered as pre-stack depth migrations. While full evaluation of the monitor surveys to static and dynamic reservoir model updates will continue beyond 2020, key initial reservoir insights are expected to emerge within days of processing completion, with some even earlier from QC volumes. Furthermore, concurrent 4D evaluations are expected to result in fruitful exchanges of ideas and technologies between fields.
- Oceania > Australia > Western Australia > North West Shelf (1.00)
- Oceania > Australia > Western Australia > Burrup Peninsula > North West Shelf (0.49)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Exmouth Basin > PL WA-59-L > Block 28/9d > Laverda Field > Macedon Formation (0.99)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Exmouth Basin > PL WA-59-L > Block 28/9a > Laverda Field > Macedon Formation (0.99)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Exmouth Basin > PL WA-59-L > Block 28/04a > Laverda Field > Macedon Formation (0.99)
- (13 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Four-dimensional and four-component seismic (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Seismic (four dimensional) monitoring (1.00)
Abstract This paper presents construction and validation of a reservoir model for the Niobrara and Codell Formations in Wattenberg Field of the Denver-Julesburg Basin. Characterization of Niobrara-Codell system is challenging because of the geologic complexity resulting from the presence of numerous faults. Because of extensive reservoir stimulation via multi-stage hydraulic fracturing, a dual-porosity model was adopted to represent the various reservoir complexities using data from geology, geophysics, petrophysics, well completion and production. After successful history matching two-and-half years of reservoir performance, the localized presence of high intensity macrofractures and resulting evolution of gas saturation was correlated with the time-lapse seismic and microseismic interpretations. The agreement between the evolved free gas saturation in the fracture system and the seismic anomalies and microseismic events pointed to the viability of the dual-porosity modeling as a tool for forecasting and future reservoir development, such as re-stimulation, infill drilling, and enhanced oil recovery strategies.
- North America > United States > Colorado > Weld County (0.37)
- North America > United States > Colorado > Denver County (0.37)
- North America > United States > Colorado > Larimer County (0.27)
- (3 more...)
- Geology > Rock Type > Sedimentary Rock (0.70)
- Geology > Structural Geology > Fault (0.69)
- Geology > Geological Subdiscipline > Geomechanics (0.46)
- North America > United States > Wyoming > Niobrara Formation (0.99)
- North America > United States > Wyoming > Laramie Basin > Niobrara Formation (0.99)
- North America > United States > Wyoming > DJ (Denver-Julesburg) Basin > Niobrara Formation (0.99)
- (13 more...)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
Reservoir Surveillance with 4DVSP - A Case Study in a Kuwait EOR Steam Flood Project
Al-Mutairi, Amal (Kuwait Oil Company) | Al-Haqqan, Hamad (Kuwait Oil Company) | Ren, Zu Biao (Kuwait Oil Company) | Tinnin, John (Baker Hughes Inc.) | Randazzo, Santi (Baker Hughes Inc.) | Pare, Antoine (Baker Hughes Inc.)
Abstract Kuwait Oil Company conducted a 4DVSP steam flood monitoring program in a heavy oil field to help optimize development options. The baseline survey for this 4DVSP was acquired in January 2016 and the monitor survey was acquired in January 2017. The key objectives for this reservoir surveillance project include acquiring a repeatable baseline survey; image two vertically stacked thin reservoir units, perform characterization to understand reservoir complexity and lateral barriers, and estimate the steam chest size (sometimes referred to as a steam chamber) after 30 days of steam injection. The 3DVSP survey took less than a week with rigless acquisition only during daylight hours. The survey area was fairly congested with infrastructure making it difficult to manoeuvre between source positions easily. To tackle this, two groups of vibrators were used with a source driven acquisition technique. This meant much of the acquisition process was automated providing better efficiency and reducing human error. The resulting data was processed and imaged with proprietary 3DVSP Kirchhoff depth migration algorithms. Due to an innovative acquisition design, output frequencies were 30% higher than achieved in previous VSPs or seismic data in the area. Velocity models were derived using the zero offset VSP data and a geomodel was derived from well data. The migration was sampled at dX/dY/dZ values of one meter each to help create a high resolution image. Synthetic seismograms from well logs and corridor stacks from the zero offset VSP were used to accurately tie the well data to the 3DVSP volume. This data volume was mapped using seismic workstations and amplitude anomalies were obvious around the steam injected well making possible the mapping of the steam chest. Deterministic inversions from this data help identify facies changes and channels explaining the direction and pathways of the steam flow. In summary, each of the goals for this project was achieved. The two thin reservoir units and the top sealing shale were resolved while inversions were very beneficial for reservoir characterization and understanding facies changes. The steam chest was easily discernable and its volume was calculated. These results justified the first ever 4DVSP in Kuwait which was acquired in January 2017. Ultimately, knowing where the steam fronts travel, where lateral barriers divert the steam, and how quickly it moves will help to optimize the development plans for the best possible EOR effectiveness and recovery rate improvement.
- Asia > Middle East > Kuwait (1.00)
- Asia > Middle East > Israel > Mediterranean Sea (0.24)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (0.56)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.40)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Near-well and vertical seismic profiles (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Thermal methods (1.00)
ABSTRACT Heavy oil reservoir monitoring is a challenging topic, which is of significant value for thermal production. The injected hot steam can drastically affect the reservoir's properties by reducing oil viscosity, which will further leads to velocity and impedance change. The drop in impedance can cause abnormally strong reflections on the top of steam chamber. In addition, the mixture of steam, oil, and water inside the steam chamber can cause strong dispersion and intense attenuation of seismic energy, resulting in obvious anomaly in frequency domain. In this paper, we show the velocity and impedance changes of oil sands before and after steam injection by lab measurements. Then by extracting the seismic attributes of both the baseline and monitorline seismic profiles, we analyzed the differences between them and found that several seismic attributes are very effective in detecting the steam chamber. These attributes either reflect the strong reflections caused by extremely low impedance of steam chamber or reveal the intense energy attenuation inside the steam chambe caused by the pore fluid mixture. Presentation Date: Thursday, September 28, 2017 Start Time: 10:35 AM Location: 370A Presentation Type: ORAL
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Geological Subdiscipline (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Thermal methods (1.00)
ABSTRACT In a time-lapse experiment, changes in a reservoir cause changes in the reflection response. We discuss a method which predicts these changes from the baseline survey and a model of the changed reservoir. This method, which takes all multiple scattering into account, is significantly more efficient than modeling the response of the entire medium containing the changed reservoir. This can be particularly attractive for applications in time-lapse full wave form inversion, which requires repeated modelling of the reflection response. Presentation Date: Monday, September 25, 2017 Start Time: 3:05 PM Location: Exhibit Hall C/D Presentation Type: POSTER
Processing Frequent 4D Land Seismic Data with Buried Sensors for CO2 Monitoring
Al Ramadhan, Abdullah (EXPEC Advanced Research Center, Saudi Aramco) | Hemyari, Emad (EXPEC Advanced Research Center, Saudi Aramco) | Bakulin, Andrey (EXPEC Advanced Research Center, Saudi Aramco) | Erickson, Kevin (EXPEC Advanced Research Center, Saudi Aramco) | Smith, Robert (EXPEC Advanced Research Center, Saudi Aramco) | Jervis, Michael A. (EXPEC Advanced Research Center, Saudi Aramco)
Abstract In 2015, Saudi Aramco started a CO2 Water-Alternating-Gas (WAG) EOR pilot project in an onshore carbonate reservoir. To monitor lateral expansion of the CO2 plume, the area was instrumented with a hybrid surface/downhole permanent seismic monitoring system. This system consists of over 1000 buried seismic sensors at a depth of around 70 m, below the the depth of expected weathering layer to mitigate the time-lapse noise. Despite receiver burial, seismic data still suffers from numerous challenges including: significant amounts of high-amplitude coherent noise such as guided waves, mode conversions, and scattered energy; amplitude variations over space and time caused by source and receiver coupling; variability of wavelet shape and arrival times due to seasonal near-surface variations; and low signal-to-noise ratio (SNR). A novel processing workflow was designed for 4D processing of such data. The workflow involves five critical processes. First, the high-amplitude coherent noise is eliminated using FK-based techniques that are 4D compliant to preserve the reservoir changes between repeated seismic surveys. Second, a four-term joint surface-consistent amplitude-scaling algorithm resolves the amplitude variations. The algorithm allows both source and receiver terms to have different scalars for the same positions, but it restricts the other two terms to be position-invariant over different time-lapse surveys, as the window of analysis does not include the reservoir. This is to guarantee that the source and receiver terms are survey-dependent while the other two terms are survey-independent. Thus, the amplitude variability is linked to source and receiver positions over space and time. It also assures that the reservoir changes are not affected by changes in the overburden. Third, wavelet shape variations are addressed using a four-term joint surface-consistent spiking deconvolution algorithm that applies similar principle as the scaling algorithm. Fourth, the small variations in reflection times between different surveys (4D statics) caused by seasonal variations are corrected by a specialized surface-consistent residual statics algorithm using a common pilot derived from the base survey. Fifth, the pre-stack data is supergrouped to enhance the signal-to-noise ratio and repeatability. The processing workflow has been applied to frequent land 3D seismic data acquired over a CO2 WAG EOR pilot project in Saudi Arabia. As a result, we obtained very repeatable seismic images that may successfully detect small CO2-related changes in a stiff carbonate reservoir.
- North America (0.93)
- Asia > Middle East > Saudi Arabia (0.90)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > Asia Government > Middle East Government > Saudi Arabia Government (0.55)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Mission Canyon Formation (0.99)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Madison Formation (0.99)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Forbisher Formation (0.99)
- (3 more...)
ABSTRACT Heavy oil reservoir's properties change dramatically during thermal production due to the viscosity drop caused by high temperature. The velocity and density decrease after hot steam injection, leading to longer travel time of seismic velocity and low impedance of steam chamber. These changes of properties can act as indicators of the steam chamber zone and can be detected through time-lapse inversion. In this paper, we first analyze the seismic profiles of baseline and monitorline survey to clarify the influence of steam-injection on reservoir's properties. Then a Modified-Cauchy prior distribution based time-lapse inversion method is applied on the field data. After that, by combining the inverted impedance and rock physics relation between impedance and temperature, the temperature distribution map is obtained. Presentation Date: Monday, October 17, 2016 Start Time: 3:20:00 PM Location: Lobby D/C Presentation Type: POSTER
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Thermal methods (1.00)
First application of two multisensor towed-streamer acquisition systems for broadband 4D analysis: Case study from offshore Angola
Charron, Patrick (Total S.A.) | Zamboni, Enrico (Total S.A.) | Palome, Salvador Pou (Total S.A.) | Smith, Patrick (WesternGeco) | Cunnell, Chris (WesternGeco) | Solorio, David (WesternGeco) | Wilk-Lopes, Monika (WesternGeco)
ABSTRACT We present a case study of a seismic experiment from offshore Angola, designed to evaluate the time-lapse (4D) compatibility of two broadband towed-streamer acquisition systems, these being a multimeasurement (PZY) acquisition monitor survey on a dual measurement (PZ) acquisition baseline survey, over a well-known field with a proven 4D effect. The 4D difference volumes and associated 4D attributes generated using data obtained at the original cable locations demonstrate good compatibility between the two systems, with consistent 4D signal and reduced noise levels compared to a conventional hydrophone-only system. This shows the potential for multisensor technology to provide 4D surveys that satisfy dual objectives: matching the spectral characteristics of a baseline survey, whilst also providing a broadband baseline for future repeats. Presentation Date: Wednesday, October 19, 2016 Start Time: 9:15:00 AM Location: 146 Presentation Type: ORAL
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Four-dimensional and four-component seismic (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
ABSTRACT One of the problems with 4D surveys is that the environmental conditions change over time so that the experiment is insufficiently repeatable. To mitigate this problem, we propose the use of interferometric least-squares migration (ILSM) to estimate the migration image for the baseline and monitor surveys. Here, a known reflector is used as the reference reflector for ILSM. Results with synthetic and field data show that ILSM can eliminate artifacts caused by non-repeatability in time-lapse surveys. Presentation Date: Tuesday, October 18, 2016 Start Time: 11:10:00 AM Location: 171/173 Presentation Type: ORAL
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (0.96)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.75)
- Geophysics > Time-Lapse Surveying > Time-Lapse Seismic Surveying (0.65)
- Europe > Norway > Norwegian Sea > Halten Terrace > PL 128 > Block 6608/10 > Norne Field > Tofte Formation (0.99)
- Europe > Norway > Norwegian Sea > Halten Terrace > PL 128 > Block 6608/10 > Norne Field > Not Formation (0.99)
- Europe > Norway > Norwegian Sea > Halten Terrace > PL 128 > Block 6608/10 > Norne Field > Ile Formation (0.99)
- (3 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (0.69)
Summary Full waveform inversion (FWI) has become an integral part of the velocity model building workflow due to its resolution, especially in shallow regimes. Usually, wideangle data are not available because of their expense, and we would like to use the power of FWI by utilizing vintage data. In these older prospects, because there is often much more geological information available than just seismic data, we can use information from wells, for example, to constrain the FWI iterations. Even though well information is at our disposal, it is difficult to incorporate it into traditional FWI that is represented by the data misfit objective function. One way to incorporate wells in the model is to build an apriori model from them and take this into account in the objective function. The objective function can be extended by a model misfit term alongside that of the data misfit. We demonstrate how the new objective function works on real data. Furthermore we introduce two workflows to recover the model difference between the baseline and the monitor or monitor surveys by using FWI in the time-lapse seismic world. Introduction The convergence of FWI to the true model is always questionable especially when the observed data lack long offsets and low frequencies. In most cases when inversion is performed on these types of datasets, we end up with a suboptimal result, even though additional information is available to constrain the FWI updates. One way to introduce additional information, from wells, is to include such information in the initial velocity model. Although that sounds intriguing, we know that we should start with a smooth model for FWI in order to avoid the local minima at the very beginning of the iterations. However, when well information is added to the initial model, it is hard to avoid the details in the starting velocity field. Also, this assumes that we always know the properties at the well location with absolute certainty, which is never the case in reality. The other solution is to build a prior model from the wells and geological interpretation and extend the objective function with the model misfit (Amir Asnaashari et al., 2012). This solution allows an interpreter to assign a confidence value to the known prior information, which can then be taken into account during the inversion. Timelapse seismic data are usually acquired to monitor reservoir–fluid movements between wells due to the production. Lately, FWI has been used to address the timelapse seismic challenges by solving model differences between the baseline and the monitor survey or surveys. In traditional time-lapse processing, comparisons are made between the uniformly processed and migrated images and conclusions are drawn based upon the data differences rather than investigating the possible model differences between the seismic acquisitions. Since the introduction of FWI in 3D form, there have been many promising techniques and workflow designs to tackle the 4D seismic processing challenges (Routh et al., 2012). A variety of approaches (independent, sequential differential inversions) are described by Raknes et al., (2013) and applied to synthetic and real data. Other alternatives are time-lapse differential waveform inversion based upon scatteringbased decomposition (Macedo et al., 2013), and the double differential method introduced by Maharramov and Biondi (2014) that follows earlier work from the wave -equation image difference-based tomography of Albertin et al., (2006).